Medium term treatment of stable stage cystic fibrosis with recombinant human DNase I

A phase II multicentre double blind placebo controlled study in 1993 showed that short term treatment (10 days) with recombinant human DNase I (rhDNase) was safe and improved pulmonary function in patients with cystic fibrosis with stable stage lung disease. A six month open label treatment study was conducted in some of the patients who participated in the short term study to assess the medium term effects of rhDNase.

Patients who completed the phase II study and were stable for 14 days prior to treatment were eligible. They were treated with rhDNase 2.5 mg twice daily for six months and reviewed at regular intervals to assess safety and efficacy.

Fifty nine patients (31M,28F) of age range 16-55 years were recruited. Mean baseline values for forced expiratory volume in one second (FEV1) and forced vital capacity (FVC) were 41.5% and 72.4% of predicted, respectively. The mean increase in FEV1 over the first month of treatment was 13.1% (range 12-14.1%) and then stabilised at 6.2% (4.6-7.8%) for the subsequent five months. FVC was similarly improved. Administration of rhDNase improved the severity of dyspnoea, cystic fibrosis related symptoms, and the modified Taussig/NIH score (not statistically significant). Fifty seven of the 59 patients completed the study; two died from progression of their pulmonary disease unrelated to treatment with rhDNase. The adverse events and intercurrent illnesses were no different from those expected in a cystic fibrosis population. Pharyngitis was the only possible drug related adverse event which occurred at least once in 14% of patients during the six month period.

Administration of rhDNase was safe, well tolerated, and improved pulmonary function in patients with cystic fibrosis. When rhDNase was stopped at day 169 there was a deterioration in pulmonary function and dyspnoea score.